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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * kexec: kexec_file_load system call
  *
  * Copyright (C) 2014 Red Hat Inc.
  * Authors:
  *      Vivek Goyal <vgoyal@redhat.com>
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/capability.h>
 #include <linux/mm.h>
 #include <linux/file.h>
 #include <linux/slab.h>
 #include <linux/kexec.h>
 #include <linux/memblock.h>
 #include <linux/mutex.h>
 #include <linux/list.h>
 #include <linux/fs.h>
 #include <linux/ima.h>
 #include <crypto/hash.h>
 #include <crypto/sha2.h>
 #include <linux/elf.h>
 #include <linux/elfcore.h>
 #include <linux/kernel.h>
 #include <linux/kernel_read_file.h>
 #include <linux/syscalls.h>
 #include <linux/vmalloc.h>
 #include "kexec_internal.h"
 
 #ifdef CONFIG_KEXEC_SIG
 static bool sig_enforce = IS_ENABLED(CONFIG_KEXEC_SIG_FORCE);
 
 void set_kexec_sig_enforced(void)
 {
     sig_enforce = true;
 }
 #endif
 
 static int kexec_calculate_store_digests(struct kimage *image);
 
 /* Maximum size in bytes for kernel/initrd files. */
 #define KEXEC_FILE_SIZE_MAX min_t(s64, 4LL << 30, SSIZE_MAX)
 
 /*
  * Currently this is the only default function that is exported as some
  * architectures need it to do additional handlings.
  * In the future, other default functions may be exported too if required.
  */
 int kexec_image_probe_default(struct kimage *image, void *buf,
                   unsigned long buf_len)
 {
     const struct kexec_file_ops * const *fops;
     int ret = -ENOEXEC;
 
     for (fops = &kexec_file_loaders[0]; *fops && (*fops)->probe; ++fops) {
         ret = (*fops)->probe(buf, buf_len);
         if (!ret) {
             image->fops = *fops;
             return ret;
         }
     }
 
     return ret;
 }
 
 void *kexec_image_load_default(struct kimage *image)
 {
     if (!image->fops || !image->fops->load)
         return ERR_PTR(-ENOEXEC);
 
     return image->fops->load(image, image->kernel_buf,
                  image->kernel_buf_len, image->initrd_buf,
                  image->initrd_buf_len, image->cmdline_buf,
                  image->cmdline_buf_len);
 }
 
 int kexec_image_post_load_cleanup_default(struct kimage *image)
 {
     if (!image->fops || !image->fops->cleanup)
         return 0;
 
     return image->fops->cleanup(image->image_loader_data);
 }
 
 /*
  * Free up memory used by kernel, initrd, and command line. This is temporary
  * memory allocation which is not needed any more after these buffers have
  * been loaded into separate segments and have been copied elsewhere.
  */
 void kimage_file_post_load_cleanup(struct kimage *image)
 {
     struct purgatory_info *pi = &image->purgatory_info;
 
     vfree(image->kernel_buf);
     image->kernel_buf = NULL;
 
     vfree(image->initrd_buf);
     image->initrd_buf = NULL;
 
     kfree(image->cmdline_buf);
     image->cmdline_buf = NULL;
 
     vfree(pi->purgatory_buf);
     pi->purgatory_buf = NULL;
 
     vfree(pi->sechdrs);
     pi->sechdrs = NULL;
 
 #ifdef CONFIG_IMA_KEXEC
     vfree(image->ima_buffer);
     image->ima_buffer = NULL;
 #endif /* CONFIG_IMA_KEXEC */
 
     /* See if architecture has anything to cleanup post load */
     arch_kimage_file_post_load_cleanup(image);
 
     /*
      * Above call should have called into bootloader to free up
      * any data stored in kimage->image_loader_data. It should
      * be ok now to free it up.
      */
     kfree(image->image_loader_data);
     image->image_loader_data = NULL;
 }
 
 #ifdef CONFIG_KEXEC_SIG
 #ifdef CONFIG_SIGNED_PE_FILE_VERIFICATION
 int kexec_kernel_verify_pe_sig(const char *kernel, unsigned long kernel_len)
 {
     int ret;
 
     ret = verify_pefile_signature(kernel, kernel_len,
                       VERIFY_USE_SECONDARY_KEYRING,
                       VERIFYING_KEXEC_PE_SIGNATURE);
     if (ret == -ENOKEY && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING)) {
         ret = verify_pefile_signature(kernel, kernel_len,
                           VERIFY_USE_PLATFORM_KEYRING,
                           VERIFYING_KEXEC_PE_SIGNATURE);
     }
     return ret;
 }
 #endif
 
 static int kexec_image_verify_sig(struct kimage *image, void *buf,
                   unsigned long buf_len)
 {
     if (!image->fops || !image->fops->verify_sig) {
         pr_debug("kernel loader does not support signature verification.\n");
         return -EKEYREJECTED;
     }
 
     return image->fops->verify_sig(buf, buf_len);
 }
 
 static int
 kimage_validate_signature(struct kimage *image)
 {
     int ret;
 
     ret = kexec_image_verify_sig(image, image->kernel_buf,
                      image->kernel_buf_len);
     if (ret) {
 
         if (sig_enforce) {
             pr_notice("Enforced kernel signature verification failed (%d).\n", ret);
             return ret;
         }
 
         /*
          * If IMA is guaranteed to appraise a signature on the kexec
          * image, permit it even if the kernel is otherwise locked
          * down.
          */
         if (!ima_appraise_signature(READING_KEXEC_IMAGE) &&
             security_locked_down(LOCKDOWN_KEXEC))
             return -EPERM;
 
         pr_debug("kernel signature verification failed (%d).\n", ret);
     }
 
     return 0;
 }
 #endif
 
 /*
  * In file mode list of segments is prepared by kernel. Copy relevant
  * data from user space, do error checking, prepare segment list
  */
 static int
 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
                  const char __user *cmdline_ptr,
                  unsigned long cmdline_len, unsigned flags)
 {
     ssize_t ret;
     void *ldata;
 
     ret = kernel_read_file_from_fd(kernel_fd, 0, &image->kernel_buf,
                        KEXEC_FILE_SIZE_MAX, NULL,
                        READING_KEXEC_IMAGE);
     if (ret < 0)
         return ret;
     image->kernel_buf_len = ret;
 
     /* Call arch image probe handlers */
     ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
                         image->kernel_buf_len);
     if (ret)
         goto out;
 
 #ifdef CONFIG_KEXEC_SIG
     ret = kimage_validate_signature(image);
 
     if (ret)
         goto out;
 #endif
     /* It is possible that there no initramfs is being loaded */
     if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
         ret = kernel_read_file_from_fd(initrd_fd, 0, &image->initrd_buf,
                            KEXEC_FILE_SIZE_MAX, NULL,
                            READING_KEXEC_INITRAMFS);
         if (ret < 0)
             goto out;
         image->initrd_buf_len = ret;
         ret = 0;
     }
 
     if (cmdline_len) {
         image->cmdline_buf = memdup_user(cmdline_ptr, cmdline_len);
         if (IS_ERR(image->cmdline_buf)) {
             ret = PTR_ERR(image->cmdline_buf);
             image->cmdline_buf = NULL;
             goto out;
         }
 
         image->cmdline_buf_len = cmdline_len;
 
         /* command line should be a string with last byte null */
         if (image->cmdline_buf[cmdline_len - 1] != '\0') {
             ret = -EINVAL;
             goto out;
         }
 
         ima_kexec_cmdline(kernel_fd, image->cmdline_buf,
                   image->cmdline_buf_len - 1);
     }
 
     /* IMA needs to pass the measurement list to the next kernel. */
     ima_add_kexec_buffer(image);
 
     /* Call arch image load handlers */
     ldata = arch_kexec_kernel_image_load(image);
 
     if (IS_ERR(ldata)) {
         ret = PTR_ERR(ldata);
         goto out;
     }
 
     image->image_loader_data = ldata;
 out:
     /* In case of error, free up all allocated memory in this function */
     if (ret)
         kimage_file_post_load_cleanup(image);
     return ret;
 }
 
 static int
 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
                int initrd_fd, const char __user *cmdline_ptr,
                unsigned long cmdline_len, unsigned long flags)
 {
     int ret;
     struct kimage *image;
     bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
 
     image = do_kimage_alloc_init();
     if (!image)
         return -ENOMEM;
 
     image->file_mode = 1;
 
     if (kexec_on_panic) {
         /* Enable special crash kernel control page alloc policy. */
         image->control_page = crashk_res.start;
         image->type = KEXEC_TYPE_CRASH;
     }
 
     ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
                        cmdline_ptr, cmdline_len, flags);
     if (ret)
         goto out_free_image;
 
     ret = sanity_check_segment_list(image);
     if (ret)
         goto out_free_post_load_bufs;
 
     ret = -ENOMEM;
     image->control_code_page = kimage_alloc_control_pages(image,
                        get_order(KEXEC_CONTROL_PAGE_SIZE));
     if (!image->control_code_page) {
         pr_err("Could not allocate control_code_buffer\n");
         goto out_free_post_load_bufs;
     }
 
     if (!kexec_on_panic) {
         image->swap_page = kimage_alloc_control_pages(image, 0);
         if (!image->swap_page) {
             pr_err("Could not allocate swap buffer\n");
             goto out_free_control_pages;
         }
     }
 
     *rimage = image;
     return 0;
 out_free_control_pages:
     kimage_free_page_list(&image->control_pages);
 out_free_post_load_bufs:
     kimage_file_post_load_cleanup(image);
 out_free_image:
     kfree(image);
     return ret;
 }
 
 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
         unsigned long, cmdline_len, const char __user *, cmdline_ptr,
         unsigned long, flags)
 {
     int ret = 0, i;
     struct kimage **dest_image, *image;
 
     /* We only trust the superuser with rebooting the system. */
     if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
         return -EPERM;
 
     /* Make sure we have a legal set of flags */
     if (flags != (flags & KEXEC_FILE_FLAGS))
         return -EINVAL;
 
     image = NULL;
 
     if (!mutex_trylock(&kexec_mutex))
         return -EBUSY;
 
     dest_image = &kexec_image;
     if (flags & KEXEC_FILE_ON_CRASH) {
         dest_image = &kexec_crash_image;
         if (kexec_crash_image)
             arch_kexec_unprotect_crashkres();
     }
 
     if (flags & KEXEC_FILE_UNLOAD)
         goto exchange;
 
     /*
      * In case of crash, new kernel gets loaded in reserved region. It is
      * same memory where old crash kernel might be loaded. Free any
      * current crash dump kernel before we corrupt it.
      */
     if (flags & KEXEC_FILE_ON_CRASH)
         kimage_free(xchg(&kexec_crash_image, NULL));
 
     ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
                      cmdline_len, flags);
     if (ret)
         goto out;
 
     ret = machine_kexec_prepare(image);
     if (ret)
         goto out;
 
     /*
      * Some architecture(like S390) may touch the crash memory before
      * machine_kexec_prepare(), we must copy vmcoreinfo data after it.
      */
     ret = kimage_crash_copy_vmcoreinfo(image);
     if (ret)
         goto out;
 
     ret = kexec_calculate_store_digests(image);
     if (ret)
         goto out;
 
     for (i = 0; i < image->nr_segments; i++) {
         struct kexec_segment *ksegment;
 
         ksegment = &image->segment[i];
         pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
              i, ksegment->buf, ksegment->bufsz, ksegment->mem,
              ksegment->memsz);
 
         ret = kimage_load_segment(image, &image->segment[i]);
         if (ret)
             goto out;
     }
 
     kimage_terminate(image);
 
     ret = machine_kexec_post_load(image);
     if (ret)
         goto out;
 
     /*
      * Free up any temporary buffers allocated which are not needed
      * after image has been loaded
      */
     kimage_file_post_load_cleanup(image);
 exchange:
     image = xchg(dest_image, image);
 out:
     if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
         arch_kexec_protect_crashkres();
 
     mutex_unlock(&kexec_mutex);
     kimage_free(image);
     return ret;
 }
 
 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
                     struct kexec_buf *kbuf)
 {
     struct kimage *image = kbuf->image;
     unsigned long temp_start, temp_end;
 
     temp_end = min(end, kbuf->buf_max);
     temp_start = temp_end - kbuf->memsz;
 
     do {
         /* align down start */
         temp_start = temp_start & (~(kbuf->buf_align - 1));
 
         if (temp_start < start || temp_start < kbuf->buf_min)
             return 0;
 
         temp_end = temp_start + kbuf->memsz - 1;
 
         /*
          * Make sure this does not conflict with any of existing
          * segments
          */
         if (kimage_is_destination_range(image, temp_start, temp_end)) {
             temp_start = temp_start - PAGE_SIZE;
             continue;
         }
 
         /* We found a suitable memory range */
         break;
     } while (1);
 
     /* If we are here, we found a suitable memory range */
     kbuf->mem = temp_start;
 
     /* Success, stop navigating through remaining System RAM ranges */
     return 1;
 }
 
 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
                      struct kexec_buf *kbuf)
 {
     struct kimage *image = kbuf->image;
     unsigned long temp_start, temp_end;
 
     temp_start = max(start, kbuf->buf_min);
 
     do {
         temp_start = ALIGN(temp_start, kbuf->buf_align);
         temp_end = temp_start + kbuf->memsz - 1;
 
         if (temp_end > end || temp_end > kbuf->buf_max)
             return 0;
         /*
          * Make sure this does not conflict with any of existing
          * segments
          */
         if (kimage_is_destination_range(image, temp_start, temp_end)) {
             temp_start = temp_start + PAGE_SIZE;
             continue;
         }
 
         /* We found a suitable memory range */
         break;
     } while (1);
 
     /* If we are here, we found a suitable memory range */
     kbuf->mem = temp_start;
 
     /* Success, stop navigating through remaining System RAM ranges */
     return 1;
 }
 
 static int locate_mem_hole_callback(struct resource *res, void *arg)
 {
     struct kexec_buf *kbuf = (struct kexec_buf *)arg;
     u64 start = res->start, end = res->end;
     unsigned long sz = end - start + 1;
 
     /* Returning 0 will take to next memory range */
 
     /* Don't use memory that will be detected and handled by a driver. */
     if (res->flags & IORESOURCE_SYSRAM_DRIVER_MANAGED)
         return 0;
 
     if (sz < kbuf->memsz)
         return 0;
 
     if (end < kbuf->buf_min || start > kbuf->buf_max)
         return 0;
 
     /*
      * Allocate memory top down with-in ram range. Otherwise bottom up
      * allocation.
      */
     if (kbuf->top_down)
         return locate_mem_hole_top_down(start, end, kbuf);
     return locate_mem_hole_bottom_up(start, end, kbuf);
 }
 
 #ifdef CONFIG_ARCH_KEEP_MEMBLOCK
 static int kexec_walk_memblock(struct kexec_buf *kbuf,
                    int (*func)(struct resource *, void *))
 {
     int ret = 0;
     u64 i;
     phys_addr_t mstart, mend;
     struct resource res = { };
 
     if (kbuf->image->type == KEXEC_TYPE_CRASH)
         return func(&crashk_res, kbuf);
 
     /*
      * Using MEMBLOCK_NONE will properly skip MEMBLOCK_DRIVER_MANAGED. See
      * IORESOURCE_SYSRAM_DRIVER_MANAGED handling in
      * locate_mem_hole_callback().
      */
     if (kbuf->top_down) {
         for_each_free_mem_range_reverse(i, NUMA_NO_NODE, MEMBLOCK_NONE,
                         &mstart, &mend, NULL) {
             /*
              * In memblock, end points to the first byte after the
              * range while in kexec, end points to the last byte
              * in the range.
              */
             res.start = mstart;
             res.end = mend - 1;
             ret = func(&res, kbuf);
             if (ret)
                 break;
         }
     } else {
         for_each_free_mem_range(i, NUMA_NO_NODE, MEMBLOCK_NONE,
                     &mstart, &mend, NULL) {
             /*
              * In memblock, end points to the first byte after the
              * range while in kexec, end points to the last byte
              * in the range.
              */
             res.start = mstart;
             res.end = mend - 1;
             ret = func(&res, kbuf);
             if (ret)
                 break;
         }
     }
 
     return ret;
 }
 #else
 static int kexec_walk_memblock(struct kexec_buf *kbuf,
                    int (*func)(struct resource *, void *))
 {
     return 0;
 }
 #endif
 
 /**
  * kexec_walk_resources - call func(data) on free memory regions
  * @kbuf:   Context info for the search. Also passed to @func.
  * @func:   Function to call for each memory region.
  *
  * Return: The memory walk will stop when func returns a non-zero value
  * and that value will be returned. If all free regions are visited without
  * func returning non-zero, then zero will be returned.
  */
 static int kexec_walk_resources(struct kexec_buf *kbuf,
                 int (*func)(struct resource *, void *))
 {
     if (kbuf->image->type == KEXEC_TYPE_CRASH)
         return walk_iomem_res_desc(crashk_res.desc,
                        IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
                        crashk_res.start, crashk_res.end,
                        kbuf, func);
     else
         return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
 }
 
 /**
  * kexec_locate_mem_hole - find free memory for the purgatory or the next kernel
  * @kbuf:   Parameters for the memory search.
  *
  * On success, kbuf->mem will have the start address of the memory region found.
  *
  * Return: 0 on success, negative errno on error.
  */
 int kexec_locate_mem_hole(struct kexec_buf *kbuf)
 {
     int ret;
 
     /* Arch knows where to place */
     if (kbuf->mem != KEXEC_BUF_MEM_UNKNOWN)
         return 0;
 
     if (!IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
         ret = kexec_walk_resources(kbuf, locate_mem_hole_callback);
     else
         ret = kexec_walk_memblock(kbuf, locate_mem_hole_callback);
 
     return ret == 1 ? 0 : -EADDRNOTAVAIL;
 }
 
 /**
  * kexec_add_buffer - place a buffer in a kexec segment
  * @kbuf:   Buffer contents and memory parameters.
  *
  * This function assumes that kexec_mutex is held.
  * On successful return, @kbuf->mem will have the physical address of
  * the buffer in memory.
  *
  * Return: 0 on success, negative errno on error.
  */
 int kexec_add_buffer(struct kexec_buf *kbuf)
 {
     struct kexec_segment *ksegment;
     int ret;
 
     /* Currently adding segment this way is allowed only in file mode */
     if (!kbuf->image->file_mode)
         return -EINVAL;
 
     if (kbuf->image->nr_segments >= KEXEC_SEGMENT_MAX)
         return -EINVAL;
 
     /*
      * Make sure we are not trying to add buffer after allocating
      * control pages. All segments need to be placed first before
      * any control pages are allocated. As control page allocation
      * logic goes through list of segments to make sure there are
      * no destination overlaps.
      */
     if (!list_empty(&kbuf->image->control_pages)) {
         WARN_ON(1);
         return -EINVAL;
     }
 
     /* Ensure minimum alignment needed for segments. */
     kbuf->memsz = ALIGN(kbuf->memsz, PAGE_SIZE);
     kbuf->buf_align = max(kbuf->buf_align, PAGE_SIZE);
 
     /* Walk the RAM ranges and allocate a suitable range for the buffer */
     ret = arch_kexec_locate_mem_hole(kbuf);
     if (ret)
         return ret;
 
     /* Found a suitable memory range */
     ksegment = &kbuf->image->segment[kbuf->image->nr_segments];
     ksegment->kbuf = kbuf->buffer;
     ksegment->bufsz = kbuf->bufsz;
     ksegment->mem = kbuf->mem;
     ksegment->memsz = kbuf->memsz;
     kbuf->image->nr_segments++;
     return 0;
 }
 
 /* Calculate and store the digest of segments */
 static int kexec_calculate_store_digests(struct kimage *image)
 {
     struct crypto_shash *tfm;
     struct shash_desc *desc;
     int ret = 0, i, j, zero_buf_sz, sha_region_sz;
     size_t desc_size, nullsz;
     char *digest;
     void *zero_buf;
     struct kexec_sha_region *sha_regions;
     struct purgatory_info *pi = &image->purgatory_info;
 
     if (!IS_ENABLED(CONFIG_ARCH_HAS_KEXEC_PURGATORY))
         return 0;
 
     zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
     zero_buf_sz = PAGE_SIZE;
 
     tfm = crypto_alloc_shash("sha256", 0, 0);
     if (IS_ERR(tfm)) {
         ret = PTR_ERR(tfm);
         goto out;
     }
 
     desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
     desc = kzalloc(desc_size, GFP_KERNEL);
     if (!desc) {
         ret = -ENOMEM;
         goto out_free_tfm;
     }
 
     sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
     sha_regions = vzalloc(sha_region_sz);
     if (!sha_regions) {
         ret = -ENOMEM;
         goto out_free_desc;
     }
 
     desc->tfm   = tfm;
 
     ret = crypto_shash_init(desc);
     if (ret < 0)
         goto out_free_sha_regions;
 
     digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
     if (!digest) {
         ret = -ENOMEM;
         goto out_free_sha_regions;
     }
 
     for (j = i = 0; i < image->nr_segments; i++) {
         struct kexec_segment *ksegment;
 
         ksegment = &image->segment[i];
         /*
          * Skip purgatory as it will be modified once we put digest
          * info in purgatory.
          */
         if (ksegment->kbuf == pi->purgatory_buf)
             continue;
 
         ret = crypto_shash_update(desc, ksegment->kbuf,
                       ksegment->bufsz);
         if (ret)
             break;
 
         /*
          * Assume rest of the buffer is filled with zero and
          * update digest accordingly.
          */
         nullsz = ksegment->memsz - ksegment->bufsz;
         while (nullsz) {
             unsigned long bytes = nullsz;
 
             if (bytes > zero_buf_sz)
                 bytes = zero_buf_sz;
             ret = crypto_shash_update(desc, zero_buf, bytes);
             if (ret)
                 break;
             nullsz -= bytes;
         }
 
         if (ret)
             break;
 
         sha_regions[j].start = ksegment->mem;
         sha_regions[j].len = ksegment->memsz;
         j++;
     }
 
     if (!ret) {
         ret = crypto_shash_final(desc, digest);
         if (ret)
             goto out_free_digest;
         ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha_regions",
                              sha_regions, sha_region_sz, 0);
         if (ret)
             goto out_free_digest;
 
         ret = kexec_purgatory_get_set_symbol(image, "purgatory_sha256_digest",
                              digest, SHA256_DIGEST_SIZE, 0);
         if (ret)
             goto out_free_digest;
     }
 
 out_free_digest:
     kfree(digest);
 out_free_sha_regions:
     vfree(sha_regions);
 out_free_desc:
     kfree(desc);
 out_free_tfm:
     kfree(tfm);
 out:
     return ret;
 }
 
 #ifdef CONFIG_ARCH_HAS_KEXEC_PURGATORY
 /*
  * kexec_purgatory_setup_kbuf - prepare buffer to load purgatory.
  * @pi:     Purgatory to be loaded.
  * @kbuf:   Buffer to setup.
  *
  * Allocates the memory needed for the buffer. Caller is responsible to free
  * the memory after use.
  *
  * Return: 0 on success, negative errno on error.
  */
 static int kexec_purgatory_setup_kbuf(struct purgatory_info *pi,
                       struct kexec_buf *kbuf)
 {
     const Elf_Shdr *sechdrs;
     unsigned long bss_align;
     unsigned long bss_sz;
     unsigned long align;
     int i, ret;
 
     sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
     kbuf->buf_align = bss_align = 1;
     kbuf->bufsz = bss_sz = 0;
 
     for (i = 0; i < pi->ehdr->e_shnum; i++) {
         if (!(sechdrs[i].sh_flags & SHF_ALLOC))
             continue;
 
         align = sechdrs[i].sh_addralign;
         if (sechdrs[i].sh_type != SHT_NOBITS) {
             if (kbuf->buf_align < align)
                 kbuf->buf_align = align;
             kbuf->bufsz = ALIGN(kbuf->bufsz, align);
             kbuf->bufsz += sechdrs[i].sh_size;
         } else {
             if (bss_align < align)
                 bss_align = align;
             bss_sz = ALIGN(bss_sz, align);
             bss_sz += sechdrs[i].sh_size;
         }
     }
     kbuf->bufsz = ALIGN(kbuf->bufsz, bss_align);
     kbuf->memsz = kbuf->bufsz + bss_sz;
     if (kbuf->buf_align < bss_align)
         kbuf->buf_align = bss_align;
 
     kbuf->buffer = vzalloc(kbuf->bufsz);
     if (!kbuf->buffer)
         return -ENOMEM;
     pi->purgatory_buf = kbuf->buffer;
 
     ret = kexec_add_buffer(kbuf);
     if (ret)
         goto out;
 
     return 0;
 out:
     vfree(pi->purgatory_buf);
     pi->purgatory_buf = NULL;
     return ret;
 }
 
 /*
  * kexec_purgatory_setup_sechdrs - prepares the pi->sechdrs buffer.
  * @pi:     Purgatory to be loaded.
  * @kbuf:   Buffer prepared to store purgatory.
  *
  * Allocates the memory needed for the buffer. Caller is responsible to free
  * the memory after use.
  *
  * Return: 0 on success, negative errno on error.
  */
 static int kexec_purgatory_setup_sechdrs(struct purgatory_info *pi,
                      struct kexec_buf *kbuf)
 {
     unsigned long bss_addr;
     unsigned long offset;
     Elf_Shdr *sechdrs;
     int i;
 
     /*
      * The section headers in kexec_purgatory are read-only. In order to
      * have them modifiable make a temporary copy.
      */
     sechdrs = vzalloc(array_size(sizeof(Elf_Shdr), pi->ehdr->e_shnum));
     if (!sechdrs)
         return -ENOMEM;
     memcpy(sechdrs, (void *)pi->ehdr + pi->ehdr->e_shoff,
            pi->ehdr->e_shnum * sizeof(Elf_Shdr));
     pi->sechdrs = sechdrs;
 
     offset = 0;
     bss_addr = kbuf->mem + kbuf->bufsz;
     kbuf->image->start = pi->ehdr->e_entry;
 
     for (i = 0; i < pi->ehdr->e_shnum; i++) {
         unsigned long align;
         void *src, *dst;
 
         if (!(sechdrs[i].sh_flags & SHF_ALLOC))
             continue;
 
         align = sechdrs[i].sh_addralign;
         if (sechdrs[i].sh_type == SHT_NOBITS) {
             bss_addr = ALIGN(bss_addr, align);
             sechdrs[i].sh_addr = bss_addr;
             bss_addr += sechdrs[i].sh_size;
             continue;
         }
 
         offset = ALIGN(offset, align);
         if (sechdrs[i].sh_flags & SHF_EXECINSTR &&
             pi->ehdr->e_entry >= sechdrs[i].sh_addr &&
             pi->ehdr->e_entry < (sechdrs[i].sh_addr
                      + sechdrs[i].sh_size)) {
             kbuf->image->start -= sechdrs[i].sh_addr;
             kbuf->image->start += kbuf->mem + offset;
         }
 
         src = (void *)pi->ehdr + sechdrs[i].sh_offset;
         dst = pi->purgatory_buf + offset;
         memcpy(dst, src, sechdrs[i].sh_size);
 
         sechdrs[i].sh_addr = kbuf->mem + offset;
         sechdrs[i].sh_offset = offset;
         offset += sechdrs[i].sh_size;
     }
 
     return 0;
 }
 
 static int kexec_apply_relocations(struct kimage *image)
 {
     int i, ret;
     struct purgatory_info *pi = &image->purgatory_info;
     const Elf_Shdr *sechdrs;
 
     sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
 
     for (i = 0; i < pi->ehdr->e_shnum; i++) {
         const Elf_Shdr *relsec;
         const Elf_Shdr *symtab;
         Elf_Shdr *section;
 
         relsec = sechdrs + i;
 
         if (relsec->sh_type != SHT_RELA &&
             relsec->sh_type != SHT_REL)
             continue;
 
         /*
          * For section of type SHT_RELA/SHT_REL,
          * ->sh_link contains section header index of associated
          * symbol table. And ->sh_info contains section header
          * index of section to which relocations apply.
          */
         if (relsec->sh_info >= pi->ehdr->e_shnum ||
             relsec->sh_link >= pi->ehdr->e_shnum)
             return -ENOEXEC;
 
         section = pi->sechdrs + relsec->sh_info;
         symtab = sechdrs + relsec->sh_link;
 
         if (!(section->sh_flags & SHF_ALLOC))
             continue;
 
         /*
          * symtab->sh_link contain section header index of associated
          * string table.
          */
         if (symtab->sh_link >= pi->ehdr->e_shnum)
             /* Invalid section number? */
             continue;
 
         /*
          * Respective architecture needs to provide support for applying
          * relocations of type SHT_RELA/SHT_REL.
          */
         if (relsec->sh_type == SHT_RELA)
             ret = arch_kexec_apply_relocations_add(pi, section,
                                    relsec, symtab);
         else if (relsec->sh_type == SHT_REL)
             ret = arch_kexec_apply_relocations(pi, section,
                                relsec, symtab);
         if (ret)
             return ret;
     }
 
     return 0;
 }
 
 /*
  * kexec_load_purgatory - Load and relocate the purgatory object.
  * @image:  Image to add the purgatory to.
  * @kbuf:   Memory parameters to use.
  *
  * Allocates the memory needed for image->purgatory_info.sechdrs and
  * image->purgatory_info.purgatory_buf/kbuf->buffer. Caller is responsible
  * to free the memory after use.
  *
  * Return: 0 on success, negative errno on error.
  */
 int kexec_load_purgatory(struct kimage *image, struct kexec_buf *kbuf)
 {
     struct purgatory_info *pi = &image->purgatory_info;
     int ret;
 
     if (kexec_purgatory_size <= 0)
         return -EINVAL;
 
     pi->ehdr = (const Elf_Ehdr *)kexec_purgatory;
 
     ret = kexec_purgatory_setup_kbuf(pi, kbuf);
     if (ret)
         return ret;
 
     ret = kexec_purgatory_setup_sechdrs(pi, kbuf);
     if (ret)
         goto out_free_kbuf;
 
     ret = kexec_apply_relocations(image);
     if (ret)
         goto out;
 
     return 0;
 out:
     vfree(pi->sechdrs);
     pi->sechdrs = NULL;
 out_free_kbuf:
     vfree(pi->purgatory_buf);
     pi->purgatory_buf = NULL;
     return ret;
 }
 
 /*
  * kexec_purgatory_find_symbol - find a symbol in the purgatory
  * @pi:     Purgatory to search in.
  * @name:   Name of the symbol.
  *
  * Return: pointer to symbol in read-only symtab on success, NULL on error.
  */
 static const Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
                           const char *name)
 {
     const Elf_Shdr *sechdrs;
     const Elf_Ehdr *ehdr;
     const Elf_Sym *syms;
     const char *strtab;
     int i, k;
 
     if (!pi->ehdr)
         return NULL;
 
     ehdr = pi->ehdr;
     sechdrs = (void *)ehdr + ehdr->e_shoff;
 
     for (i = 0; i < ehdr->e_shnum; i++) {
         if (sechdrs[i].sh_type != SHT_SYMTAB)
             continue;
 
         if (sechdrs[i].sh_link >= ehdr->e_shnum)
             /* Invalid strtab section number */
             continue;
         strtab = (void *)ehdr + sechdrs[sechdrs[i].sh_link].sh_offset;
         syms = (void *)ehdr + sechdrs[i].sh_offset;
 
         /* Go through symbols for a match */
         for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
             if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
                 continue;
 
             if (strcmp(strtab + syms[k].st_name, name) != 0)
                 continue;
 
             if (syms[k].st_shndx == SHN_UNDEF ||
                 syms[k].st_shndx >= ehdr->e_shnum) {
                 pr_debug("Symbol: %s has bad section index %d.\n",
                         name, syms[k].st_shndx);
                 return NULL;
             }
 
             /* Found the symbol we are looking for */
             return &syms[k];
         }
     }
 
     return NULL;
 }
 
 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
 {
     struct purgatory_info *pi = &image->purgatory_info;
     const Elf_Sym *sym;
     Elf_Shdr *sechdr;
 
     sym = kexec_purgatory_find_symbol(pi, name);
     if (!sym)
         return ERR_PTR(-EINVAL);
 
     sechdr = &pi->sechdrs[sym->st_shndx];
 
     /*
      * Returns the address where symbol will finally be loaded after
      * kexec_load_segment()
      */
     return (void *)(sechdr->sh_addr + sym->st_value);
 }
 
 /*
  * Get or set value of a symbol. If "get_value" is true, symbol value is
  * returned in buf otherwise symbol value is set based on value in buf.
  */
 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
                    void *buf, unsigned int size, bool get_value)
 {
     struct purgatory_info *pi = &image->purgatory_info;
     const Elf_Sym *sym;
     Elf_Shdr *sec;
     char *sym_buf;
 
     sym = kexec_purgatory_find_symbol(pi, name);
     if (!sym)
         return -EINVAL;
 
     if (sym->st_size != size) {
         pr_err("symbol %s size mismatch: expected %lu actual %u\n",
                name, (unsigned long)sym->st_size, size);
         return -EINVAL;
     }
 
     sec = pi->sechdrs + sym->st_shndx;
 
     if (sec->sh_type == SHT_NOBITS) {
         pr_err("symbol %s is in a bss section. Cannot %s\n", name,
                get_value ? "get" : "set");
         return -EINVAL;
     }
 
     sym_buf = (char *)pi->purgatory_buf + sec->sh_offset + sym->st_value;
 
     if (get_value)
         memcpy((void *)buf, sym_buf, size);
     else
         memcpy((void *)sym_buf, buf, size);
 
     return 0;
 }
 #endif /* CONFIG_ARCH_HAS_KEXEC_PURGATORY */
 
 int crash_exclude_mem_range(struct crash_mem *mem,
                 unsigned long long mstart, unsigned long long mend)
 {
     int i, j;
     unsigned long long start, end, p_start, p_end;
     struct crash_mem_range temp_range = {0, 0};
 
     for (i = 0; i < mem->nr_ranges; i++) {
         start = mem->ranges[i].start;
         end = mem->ranges[i].end;
         p_start = mstart;
         p_end = mend;
 
         if (mstart > end || mend < start)
             continue;
 
         /* Truncate any area outside of range */
         if (mstart < start)
             p_start = start;
         if (mend > end)
             p_end = end;
 
         /* Found completely overlapping range */
         if (p_start == start && p_end == end) {
             mem->ranges[i].start = 0;
             mem->ranges[i].end = 0;
             if (i < mem->nr_ranges - 1) {
                 /* Shift rest of the ranges to left */
                 for (j = i; j < mem->nr_ranges - 1; j++) {
                     mem->ranges[j].start =
                         mem->ranges[j+1].start;
                     mem->ranges[j].end =
                             mem->ranges[j+1].end;
                 }
 
                 /*
                  * Continue to check if there are another overlapping ranges
                  * from the current position because of shifting the above
                  * mem ranges.
                  */
                 i--;
                 mem->nr_ranges--;
                 continue;
             }
             mem->nr_ranges--;
             return 0;
         }
 
         if (p_start > start && p_end < end) {
             /* Split original range */
             mem->ranges[i].end = p_start - 1;
             temp_range.start = p_end + 1;
             temp_range.end = end;
         } else if (p_start != start)
             mem->ranges[i].end = p_start - 1;
         else
             mem->ranges[i].start = p_end + 1;
         break;
     }
 
     /* If a split happened, add the split to array */
     if (!temp_range.end)
         return 0;
 
     /* Split happened */
     if (i == mem->max_nr_ranges - 1)
         return -ENOMEM;
 
     /* Location where new range should go */
     j = i + 1;
     if (j < mem->nr_ranges) {
         /* Move over all ranges one slot towards the end */
         for (i = mem->nr_ranges - 1; i >= j; i--)
             mem->ranges[i + 1] = mem->ranges[i];
     }
 
     mem->ranges[j].start = temp_range.start;
     mem->ranges[j].end = temp_range.end;
     mem->nr_ranges++;
     return 0;
 }
 
 int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
               void **addr, unsigned long *sz)
 {
     Elf64_Ehdr *ehdr;
     Elf64_Phdr *phdr;
     unsigned long nr_cpus = num_possible_cpus(), nr_phdr, elf_sz;
     unsigned char *buf;
     unsigned int cpu, i;
     unsigned long long notes_addr;
     unsigned long mstart, mend;
 
     /* extra phdr for vmcoreinfo ELF note */
     nr_phdr = nr_cpus + 1;
     nr_phdr += mem->nr_ranges;
 
     /*
      * kexec-tools creates an extra PT_LOAD phdr for kernel text mapping
      * area (for example, ffffffff80000000 - ffffffffa0000000 on x86_64).
      * I think this is required by tools like gdb. So same physical
      * memory will be mapped in two ELF headers. One will contain kernel
      * text virtual addresses and other will have __va(physical) addresses.
      */
 
     nr_phdr++;
     elf_sz = sizeof(Elf64_Ehdr) + nr_phdr * sizeof(Elf64_Phdr);
     elf_sz = ALIGN(elf_sz, ELF_CORE_HEADER_ALIGN);
 
     buf = vzalloc(elf_sz);
     if (!buf)
         return -ENOMEM;
 
     ehdr = (Elf64_Ehdr *)buf;
     phdr = (Elf64_Phdr *)(ehdr + 1);
     memcpy(ehdr->e_ident, ELFMAG, SELFMAG);
     ehdr->e_ident[EI_CLASS] = ELFCLASS64;
     ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
     ehdr->e_ident[EI_VERSION] = EV_CURRENT;
     ehdr->e_ident[EI_OSABI] = ELF_OSABI;
     memset(ehdr->e_ident + EI_PAD, 0, EI_NIDENT - EI_PAD);
     ehdr->e_type = ET_CORE;
     ehdr->e_machine = ELF_ARCH;
     ehdr->e_version = EV_CURRENT;
     ehdr->e_phoff = sizeof(Elf64_Ehdr);
     ehdr->e_ehsize = sizeof(Elf64_Ehdr);
     ehdr->e_phentsize = sizeof(Elf64_Phdr);
 
     /* Prepare one phdr of type PT_NOTE for each present CPU */
     for_each_present_cpu(cpu) {
         phdr->p_type = PT_NOTE;
         notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
         phdr->p_offset = phdr->p_paddr = notes_addr;
         phdr->p_filesz = phdr->p_memsz = sizeof(note_buf_t);
         (ehdr->e_phnum)++;
         phdr++;
     }
 
     /* Prepare one PT_NOTE header for vmcoreinfo */
     phdr->p_type = PT_NOTE;
     phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
     phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
     (ehdr->e_phnum)++;
     phdr++;
 
     /* Prepare PT_LOAD type program header for kernel text region */
     if (need_kernel_map) {
         phdr->p_type = PT_LOAD;
         phdr->p_flags = PF_R|PF_W|PF_X;
         phdr->p_vaddr = (unsigned long) _text;
         phdr->p_filesz = phdr->p_memsz = _end - _text;
         phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);
         ehdr->e_phnum++;
         phdr++;
     }
 
     /* Go through all the ranges in mem->ranges[] and prepare phdr */
     for (i = 0; i < mem->nr_ranges; i++) {
         mstart = mem->ranges[i].start;
         mend = mem->ranges[i].end;
 
         phdr->p_type = PT_LOAD;
         phdr->p_flags = PF_R|PF_W|PF_X;
         phdr->p_offset  = mstart;
 
         phdr->p_paddr = mstart;
         phdr->p_vaddr = (unsigned long) __va(mstart);
         phdr->p_filesz = phdr->p_memsz = mend - mstart + 1;
         phdr->p_align = 0;
         ehdr->e_phnum++;
         pr_debug("Crash PT_LOAD ELF header. phdr=%p vaddr=0x%llx, paddr=0x%llx, sz=0x%llx e_phnum=%d p_offset=0x%llx\n",
             phdr, phdr->p_vaddr, phdr->p_paddr, phdr->p_filesz,
             ehdr->e_phnum, phdr->p_offset);
         phdr++;
     }
 
     *addr = buf;
     *sz = elf_sz;
     return 0;
 }

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